Video display systems generally display an image as an M.times.N array of pixels. In one particular class of video display systems, known as optical projection systems, one or more beams of light are modulated in accordance with electrical signals received from an electronic controller. In the case of a single modulated beam, the beam is scanned horizontally in successive lines on a screen to develop the image. With multiple modulated beams, each beam may be used to scan one row, respectively, in the image. The multiple beams would be simultaneously scanned horizontally across the screen. During the horizontal scanning, the beam intensity in each beam is modulated for each column of pixels to form the image.
A multiple beam system is disclosed in copending, commonly owned application, Ser. No. 429,987, filed Nov. 1, 1989, entitled "UNIQUE MODULATION TELEVISION." The disclosed multiple beam system includes an M.times.1 mirror array where M is equal to the number of horizontal lines in the pixel array. The mirrors in the array are pivotally mounted along one of their edges to a base plate. Mounted to an opposite edge of each mirror and also to the base plate is a piezoelectric crystal, such that there is one piezoelectric crystal for each mirror. The mirror array is uniformly illuminated and the reflected light beam from each mirror is incident upon a slit. By applying electrical signals to the piezoelectric crystals, the position of each of the mirrors is altered, thereby causing a slight deviation in the path of each of the reflected beams. As the path of each beam is changed, the amount of light from each beam which passes through the slit is modulated, thereby modulating the intensity of the beam. Each modulated beam is then incident upon a rotating polygonal mirror which horizontally sweeps each of the beams across the screen. As the beams are being horizontally swept, the electrical signals to each of the piezoelectric crystals may be changing to vary the intensity for each column of pixels in the resultant displayed image. As disclosed in this prior filed application, the electrical signals are exemplarily provided by clocking data from a bit mapped memory, wherein the data clock is synchronous with the scan rate in the pixel array.
The rotating mirror which provides the horizontal sweep may be eliminated by providing an M.times.N mirror array. The reflected beam from each mirror is used to develop each pixel in the displayed M.times.N raster. An example of a video display system using an M.times.N mirror ray is disclosed in copending commonly owned application, Ser. No. 448,748, filed Dec. 11, 1989, entitled "UNIQUE MODULATION TELEVISION." Similarly to the system disclosed in the above mentioned prior filed application, each beam is modulated by applying an electric signal to each piezoelectric crystal under each mirror.